This invention is an improved doppler microwave radar simulator which simulates a moving earth, without moving components, so as to minimize weight, complexity and size.
Aircraft microwave doppler/range radar systems for testing aircraft without the need to fly the aircraft have been suggested in the past. Such known test systems have employed such methods as coupling the output to the input by means of feed horns and suitable waveguides, R.F. feed horns intercepting antenna beams, utilizing a rotating drum or disk to impart a doppler shift or delay to the signal transmitted, also using a common household window fan suitably located with respect to the system antenna. Such known test systems are large and/or the results obtained are not accurately repeatable to insure a measure of confidence in the test system. Moreover the environment on an aircraft flight line is generally considered to include the possibility of an explosive atmosphere because of the presence of aviation fuel. Examples of known doppler target simulators and doppler antenna calibration apparatus are disclosed in U.S. Pat. Nos. 3329953; 3787866; 3142059; 3665616 and 3108275.
The present invention provides an electronic microwave doppler/range/test simulator and a method of operating the same which overcome the foregoing disadvantages and is suitable as a flight-line device of reduced weight, complexity and size.